1. Field of Invention
The present invention relates to a button structure and design method. More particularly, the present invention relates to a button structure and design method for preventing the latching of buttons.
2. Description of Related Art
Keyboard provides an essential communication interface between users and their electronic products. As the need for electronic products continues to increase, different types of key button structures and design methods are also developed. If, for whatever reason, the button is momentarily latched when the button is pressed, smoothness of the keying operation is affected. Therefore, providing a latch-free button structure and design method is critical to the keyboard operation.
FIGS. 1A and 1B are schematic views showing the configuration of one of the buttons inside a conventional electronic product before and after the button is pressed. As shown in FIG. 1A, the electronic product 10 includes at least a housing 20, a plurality of buttons 30 (only one is shown) and a printed circuit board (PCB) 40. The button 30 comprises a cap body 32 and a contact rod 34 attached to the bottom section of the cap body 32. The circuit board 40 is placed inside the housing 20 and the button 30 is positioned between the housing 20 and the circuit board 40. The upper section of the cap body 32 is exposed to the top through the housing 20. Through the pressing action provided by a user, the contact rod 34 underneath the button 30 touches an electrical contact 42 on the circuit board 40 leading to electrical conduction.
As shown in FIG. 1B, dimensional tolerance of the buttons 30 in most electronic products 10 is generally loose. When a user presses on the cap body 32 of the button 30 so that the contact rod 34 touches the contact point 42 on the circuit board 40, the cap body 32 may deform momentarily and press against the sides of the housing 20. If point a of the cap body 32 is pushed below point c or point a is caught between point b and point c of the sidewall 22 of the housing (as shown in FIG. 1B), the cap body 32 is easily latched to the sidewall 22. As a result, the button 30 has difficulties returning to its original position after the pressure on the button 30 is released leading to a slowdown of typing.